1. Field of the Invention
The present invention relates to a communication system for an automatic tracking type survey unit.
2. Description of the Related Art
There has been known a surveying instrument for automatically tracking a tracking target by measuring a distance to the tracking target, an angle (hereinafter referred to as xe2x80x9chorizontal anglexe2x80x9d) formed by a direction in which a tracking target is present with respect to a reference direction, and an angle (hereinafter referred to as xe2x80x9celevation anglexe2x80x9d) formed by a direction in which a tracking target is present with respect to a reference height.
FIG. 13 shows a conventional communication system for a surveying instrument for automatically controlling a construction machine using an automatic tracking type survey unit. In this figure, reference numeral 1 designates an automatic tracking type survey unit. The automatic tracking type survey unit I is installed at a known point O set as a reference position in a working site. A personal computer 2 is connected to the automatic tracking type survey unit 1, and a radio transmitter 3 is connected to the personal computer 2.
A bulldozer 4 as a construction machine is provided with a blade 5 as a ground leveling implement. A pole 6 is stood up on the blade 5, and a prism 7 used as a tracking target is provided on the pole 6. The bulldozer 4 is provided with a radio receiver 8 for receiving an electric wave transmitted from the radio transmitter 3.
Finished height data (described later) at respective horizontal coordinate positions in the working site is stored in the personal computer 2. The automatic tracking type survey unit 1 tracks the prism 7 to measure the distance from the known point O to the prism 7, and the horizontal angle from the reference direction to the direction in which the prism 7 is present for determining a horizontal coordinate position of the prism 7 with the known point O as a reference. The data of the horizontal coordinate position is transmitted from the automatic tracking type survey unit 1 to the personal computer 2.
The personal computer 2 reads out the finished height data of ground at the determined horizontal coordinate position to send the data to the radio transmitter 3. The radio transmitter 3 transmits the finished height data, as information relating to the surveying work, to the radio receiver 8, and the bulldozer 4 controls the blade 5 by a hydraulic controller 9 on the basis of the finished height data received by the radio receiver 8. The blade 5 excavates or cuts the ground to form a finished plane of the designed finished height (i.e., construction height).
However, according to the conventional communication system between the surveying instrument side and the construction working machinery side, in the working site, generally, operators use transceivers to keep in contact with each other, and electric wave noises generated by the construction machine are present. Therefore, radio interference or communication trouble tends to occur in communication between the surveying instrument side and the construction machine side. Due to this fact, information relating to the surveying work transmitted by the surveying instrument is sometimes not transmitted accurately to the tracking target on the construction machine side.
It is an object of this invention to provide a communication system for a surveying instrument which is hard to generate radio interference or communication trouble even under the presence of electric wave noises and the like.
For achieving the aforementioned object, according to a first aspect of the present invention, there is provided a communication system for a surveying instrument in which a survey unit irradiates tracking light toward a tracking target, the tracking light is then reflected by the tracking target, the tracking light reflected from the tracking target is then received by light receiving means in the survey unit to thereby automatically track the tracking target, modulation means modulates the tracking light to transmit information relating to a surveying work toward the tracking target, a light receiving element provided on the tracking target then receives the tracking light, and demodulation means demodulates the tracking light received by the light receiving element.
Thus, there is exhibited an effect that the survey unit communicates with the tracking target through optical communication using the modulated tracking light, and information relating to the surveying work can be transmitted while avoiding radio interference or communication trouble even under the presence of electric wave noises or the like. In particular, since the survey unit automatically tracks the tracking target, the directivity of the tracking light with respect to the tracking target is enhanced, and the efficient transmission of information is accomplished by using the tracking light also for communication.
According to, a second aspect of the present invention, there is provided a communication system for a surveying instrument in which the tracking target is horizontally rotatable together with the light receiving element and is automatically directed at the survey unit on the basis of a light receiving output of the light receiving element.
Thus, there is exhibited an effect that even if a change occurs in a relative positional relationship between the survey unit and the tracking target, the survey unit can keep tracking the tracking target.
According to a third aspect of the present invention, there is provided a communication system for a surveying instrument in which the survey unit is installed at a known point to designate respective points of a working site as coordinates with the known point defined as a reference, a tracking target is provided on a leveling implement of a construction machine, the construction machine has ground leveling implement control means for controlling a ground leveling implement, the working site is leveled by the ground leveling implement to form a finished plane, finished height data memory means on the survey unit side stores heights from the known point at respective horizontal coordinate positions of the finished plane as finished height data, horizontal coordinate position determination means determines a horizontal coordinate position of the tracking target, arithmetic means calculates a deviation from a target height of the tracking target at the horizontal coordinate position on the basis of the finished height data relative to the determined horizontal coordinate position, the deviation is transmitted as information relating to the surveying work toward the tracking target, and the ground leveling implement control means adjusts a height position of the ground leveling implement so that the tracking target is made closer to the target height on the basis of the result of reception of the tracking target whereby a ground at the determined horizontal coordinate position is leveled into the finished plane.
Thus, there is exhibited an effect that automated and efficient construction work can be accomplished.
According to a fourth aspect of the present invention, there is provided a communication system for a surveying instrument in which the survey unit irradiates tracking light toward a tracking target, the tracking target then reflects the tracking light, light receiving means in the survey unit receives the tracking light reflected from the tracking target to thereby automatically track the tracking target, and light receiving means provided on the tracking target sends modulated light including information relating to a surveying work toward the survey unit.
Thus, there is exhibited an effect similar to that of the first aspect in that the survey unit communicates with the tracking target through optical communication using modulated light from the light receiving means.